Field of the Invention
The present invention relates to an improvement of a differential device, particularly the differential device which includes: an annular input member into which rotational force is inputted; a cross-shaped shaft body integrally including a first shaft having both end portions supported on the input member, and a second shaft orthogonal to the first shaft, the cross-shaped shaft body configured to rotate integrally with the input member around an axis of the second shaft, a pinion rotatably supported on the first shaft; and a pair of side gears meshing with the pinion and respectively connected to a pair of output shafts, the differential device configured to distributively transmit the rotational force which is transmitted from the input member to the cross-shaped shaft body to the pair of output shafts via the pinion and the pair of side gears.
Description of the Related Art
Conventionally, such a differential device has been publicly known as described in U.S. Pat. No. 8,360,921, for example. In this conventional differential device, a pinion shaft (a first shaft) is directly fixed to an annular input member, which enables omission of a differential case for performing power transmission between the annular input member and the pinion shaft. However, in order to retain the side gears at positions where the side gears are meshed with the pinions, it is necessary to specially provide a side-gear retaining case for housing a differential mechanism therein.
In the conventional differential device, even though the differential case for the power transmission can be omitted, it is necessary to provide the relatively large side gear retaining case for housing the differential mechanism including the pinions, the pinion shaft and the side gears. For this reason, there is a problem that the omission of the differential case does not lead to sufficient simplification of a structure and weight reduction in the differential device as a whole. Furthermore, there are problems such as difficulty in accuracy assurance of the differential mechanism alone and the like, because the differential mechanism cannot be assembled as a single unit with predetermined precision unless the side gear retaining case is integrally assembled to the differential mechanism.